CN109836548B - Preparation method of environment-friendly melamine-based foam plastic - Google Patents
Preparation method of environment-friendly melamine-based foam plastic Download PDFInfo
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Abstract
The invention discloses a preparation method of environment-friendly melamine-based foam plastic. Firstly, adding melamine, paraformaldehyde and water into a reactor, adding a modified monomer, adjusting the pH value of a solution, and then carrying out steam heating reaction; adding an aldehyde-removing functional monomer after the reaction, and continuously stirring for reaction to obtain the expandable low-formaldehyde melamine-based resin; sequentially adding an emulsifier, a compound curing agent and a foaming agent into an auxiliary agent reaction kettle and uniformly mixing to obtain a mixed auxiliary agent; cooling the obtained resin, then respectively metering and simultaneously feeding the resin and the mixed auxiliary agent into a double-screw machine for high-speed emulsification, and performing microwave foaming after emulsification to obtain melamine-based foam M1; finally, the melamine-based foam M1 is dried and microwave-dried by superheated steam in sequence, and the environment-friendly melamine-based foam plastic product is obtained after drying. The invention realizes the industrial production of the melamine-based foam plastic product with zero formaldehyde release, and solves the key indexes of melamine-based foam plastic industrialization and the bottleneck of environment protection and safety process.
Description
The technical field is as follows:
the invention belongs to the technical field of material preparation, and particularly relates to a preparation method of environment-friendly melamine-based foam plastic.
Secondly, background art:
the melamine-based foam plastic is also called melamine foam plastic, and is a three-dimensional network cross-linked structure with the aperture ratio of more than 99 percent, which is obtained by microwave foaming of melamine formaldehyde resin, and the product has the comprehensive properties of excellent sound absorption, flame retardance, heat insulation, fungus resistance, friction, sanitary safety, good secondary processability and the like. The characteristics enable the product to be widely applied to the fields of aerospace, navigation and aviation, building venues, factory construction, air conditioning equipment, rail transit, electronic products, biological pollution control engineering and the like, particularly used under the environment conditions with strict requirements on flame retardance, high temperature, high frequency sound absorption and light weight, and become a new material which cannot be replaced by the new domestic material world and a novel environment-friendly material with huge development prospect in the 21 st century. However, the melamine-based foam plastics sold in the current market have high formaldehyde release, pollute the environment and influence the physical and psychological health of people, thus seriously hindering the popularization of the application range of the product and limiting the market application field.
At present, there are also a number of reports on melamine foams. For example: 1. patent CN104602802A discloses a process for the preparation of melamine/formaldehyde foams. According to the invention, after the melamine formaldehyde precondensate is added with water and redissolved, an emulsifier, a foaming agent, a curing agent, a stabilizer, a coloring agent, an ultraviolet absorbent and other auxiliaries are added, the melamine foam plastic is prepared by high-speed emulsification and microwave radiation foaming, and finally the obtained product is annealed and dried by hot air to obtain the melamine foam plastic. 2. The invention patent application CN107474207A discloses a preparation process of low-formaldehyde melamine foam plastic, which comprises the steps of adding melamine into a certain amount of formaldehyde solution, adding chelating agent sodium citrate and sodium phosphate, adopting melamine formaldehyde resin of microwave batch reaction, then adding emulsifier, foaming agent and curing agent for emulsification and stirring, and then sending to a far infrared heating furnace for high-temperature baking for 1-2 hours to obtain the low-formaldehyde melamine foam plastic.
Thirdly, the invention content:
the technical problem to be solved by the invention is as follows: according to the existing state of the existing melamine foam plastic preparation technology, the invention provides a novel environment-friendly melamine foam plastic industrial preparation method. By adopting the technical scheme of the invention, the industrial production of the melamine-based foam plastic product with zero formaldehyde release is realized, and the key indexes of melamine-based foam plastic industrialization and the bottleneck of environment-friendly and safe processes are solved.
In order to solve the problems, the invention adopts the technical scheme that:
the invention provides a preparation method of environment-friendly melamine-based foam plastic, which comprises the following steps:
(1) preparation of expandable low-formaldehyde melamine-based resin:
a. melamine, paraformaldehyde and water are used as main raw materials; the addition amounts of the three main raw materials are 40-60 parts of melamine, 25-35 parts of paraformaldehyde and 25-40 parts of water (preferably 44-48 parts of melamine, 30-35 parts of paraformaldehyde and 35-40 parts of water) respectively in parts by weight;
b. weighing melamine, paraformaldehyde and water according to the proportion of the three main raw materials in the step a, adding the weighed three raw materials into a reactor, adding a modified monomer, adding a sodium hydroxide solution to adjust the pH value to 8-9, heating by adopting steam, and reacting at constant temperature for 1-3 hours when the reaction temperature is increased to 80-100 ℃ (preferably 90-100 ℃);
the addition amount of the modified monomer is 0.5-5% (preferably 1-2%) of the addition amount of the raw material melamine;
c. after the reaction in the step b, cooling the obtained reaction liquid to 20-40 ℃ (preferably 30-40 ℃), then adding the formaldehyde-removing functional monomer, continuing stirring and reacting for 1-3 hours under the reaction temperature condition, and obtaining the expandable low-formaldehyde melamine-based resin after the reaction;
the addition amount of the aldehyde-removing functional monomer is 0.1-5% (preferably 1-3%) of the addition amount of melamine;
(2) preparation of mixed auxiliary agent:
25-35 parts of emulsifier, 30-40 parts of compound curing agent and 40-55 parts of foaming agent (preferably 28-32 parts of emulsifier, 31-36 parts of compound curing agent and 40-45 parts of foaming agent) are sequentially added into an auxiliary reaction kettle to be rapidly stirred and uniformly mixed (the stirring speed is 720 revolutions per second, and the stirring time is 30 minutes); after uniformly mixing, slowly stirring (the stirring speed is 300 revolutions per second) for later use;
(3) preparation of melamine-based foam M1:
cooling the expandable low-formaldehyde melamine resin prepared in the step (1) to 0 ℃ through a single screw, and then feeding the expandable low-formaldehyde melamine resin into a double-screw machine through a metering screw, wherein the flow rate of the metering screw is 1.5 to 2.5Kg/min (accurate to g/min, preferably 2.0 to 2.5 Kg/min); the mixed assistant obtained in the step (2) and the expandable low-formaldehyde melamine-based resin enter a double-screw machine simultaneously through a metering pump, and the flow of the metering pump is 400-; mixing the expandable low-formaldehyde melamine-based resin and the mixing aid in a double-screw machine for high-speed emulsification (the rotating speed of the screw is 110 revolutions per minute), uniformly distributing the emulsified materials, then sending the materials into a microwave oven for foaming, wherein the microwave foaming power is 90-120Kw (preferably 100-110Kw), the microwave foaming time is 15-30 minutes (preferably 20-30 minutes), and obtaining melamine-based foam M1 after microwave irradiation foaming;
(4) optimization of melamine based foams:
drying the melamine-based foam M1 obtained in the step (3) by using superheated steam; after the superheated steam is dried, the product is dried again by a microwave oven, and finally the environment-friendly melamine-based foam plastic product is obtained.
According to the preparation method of the environment-friendly melamine-based foam plastic, the mass percentage concentration of the sodium hydroxide solution is 10-30%.
According to the preparation method of the environment-friendly melamine-based foam plastic, the modified monomer is at least one of thiourea, bisphenol A, polyvinyl alcohol, hydroxybutyronitrile latex, basic copper carbonate, superfine polyimide resin powder, polyamide 66, polyamide 6, polyamide 610, polyamide 612, benzoguanamine, tris- (2-hydroxyethyl) isocyanate, potassium dihydrogen phosphate, sodium tripolyphosphate, sodium tetraborate, triphenylboron, trimethoxysilane, sodium silicate and sodium metasilicate.
According to the preparation method of the environment-friendly melamine-based foam plastic, the aldehyde-removing functional monomer is at least one of 2-imidazolidinone, N-chloroformyl-2-imidazolidinone, 1, 3-dimethyl-2-imidazolidinone, N-acetyl-2-imidazolidinone, melamine, hydrogen peroxide, sodium thiosulfate, nano titanium dioxide, acetanilide, hexamethylenediamine, thiourea, N-methylethylamine, ammonia water and hydrazine carbonate.
According to the preparation method of the environment-friendly melamine-based foam plastic, the emulsifier in the step (2) is an anionic surfactant;
the compound curing agent is a mixture of an organic acid and a latent high-temperature curing agent, and the mass ratio of the organic acid to the latent high-temperature curing agent is 1:1-3 (preferably 1: 2).
According to the preparation method of the environment-friendly type melamine-based foam plastic, the anionic surfactant is any one of sodium fatty alcohol sulfate, sodium ethoxylated fatty acid methyl ester sulfonate, sodium alkyl naphthalene sulfonate, secondary alkyl sodium sulfonate, alpha-alkenyl sodium sulfonate, sodium dodecyl benzene sulfonate, sodium fatty alcohol polyglycol ether sulfate, sodium lauryl polyoxyethylene ether sulfate, alpha-sulfo fatty acid methyl ester, sodium cocoyl hydroxyethyl sulfonate and sodium dodecyl alcohol polyoxyethylene ether carboxylate;
the organic acid is acetic acid, oxalic acid, formic acid, p-toluenesulfonic acid or 2-acrylamido-2-methylpropanesulfonic acid;
the latent high-temperature curing agent is methyl hexahydrophthalic anhydride, phthalic anhydride, dicyandiamide, ethylene urea, polyimide, maleic anhydride or polyacrylic acid;
the foaming agent is n-pentane.
According to the preparation method of the environment-friendly melamine-based foam plastic, the temperature of the microwave oven body in the step (3) is 70-100 ℃.
According to the preparation method of the environment-friendly type melamine-based foamed plastic, the drying section box body adopted in the superheated steam drying process in the step (4) is 10 meters long, 1 meter high and 1.2 meters wide (the width of the product environment-friendly type melamine-based foamed plastic is 1.18 meters and the height is 0.9 meters), a grid belt is arranged on the bottom of the box body, the belt speed is 0.1-0.5 meter/minute, and meshes with the diameter of 0.5cm (used for releasing small molecular substances such as formaldehyde and foaming agent carried by superheated steam passing through the foamed plastic to a tail gas treatment system) are fully distributed in the bottom of the box body within 0.5 meter from the central line; the negative pressure environment in the drying process is-150 pa, and the temperature of the superheated steam is 160 ℃.
According to the preparation method of the environment-friendly melamine-based foamed plastic, the microwave power is 1-5KW in the secondary drying process of the microwave oven, the conveying speed of the belt is 0.1-0.5 m/min, and the temperature of the box body of the microwave oven is 80-120 ℃.
The invention has the following positive beneficial effects:
1. according to the technical scheme, the molar ratio among the raw materials, the resin modification and the addition of the formaldehyde-removing functional monomer are optimized, so that the expandable low-formaldehyde melamine-based resin is prepared, and the content of free formaldehyde in the obtained resin is reduced to 0.13% from 0.5%.
2. The raw material selected by the invention is paraformaldehyde solid, and compared with a formaldehyde solution, the invention has the advantages of convenient storage, stable reaction, difficult volatilization and the like. The resin and the foam plastic have lower formaldehyde content when the addition amount of paraformaldehyde is less, but the too low addition amount of formaldehyde causes low crosslinking degree and more active groups in the reaction stage of the resin, so that the storage time of the resin is short and the physical properties of the foam plastic are poor; too high formaldehyde addition can increase the formaldehyde release content of the product although the resin and the foam plastic have stable performance; it is important to select an appropriate amount to be added. The invention obtains better adding amount through optimization.
3. The technical scheme of the invention is that a modified monomer is added, the purpose of adding the modified monomer is to improve the resin crosslinking degree and enhance the strength and temperature resistance of the foam plastic, the addition of the modified monomer enables the tearing strength of the foam plastic to be improved from 30N/M to 65N/M, the tensile strength to be improved from 82kPa to 185kPa, the indentation hardness to be improved from 398N to 545N, and the resilience to be improved from 55% to 75%; the temperature resistance of the obtained foam is improved from 240 ℃ to 265 ℃.
4. According to the technical scheme, the selection of the emulsifier initially influences the dispersibility of the resin, and finally influences the aperture size and fineness of the melamine-based foam plastic, the small molecular formaldehyde and other substances can quickly overflow from the large cells in the later optimization stage, but the final sound absorption effect and physical strength of the product are influenced by the large cells. Therefore, it is also important to select an appropriate emulsifier and an appropriate amount to be added. The invention obtains the better adding amount of the emulsifier through optimization.
5. According to the technical scheme, a compound curing agent (the mixture of the organic acid and the potential high-temperature curing agent) is adopted, so that the organic acid is cured and crosslinked in a microwave irradiation stage, secondary curing is performed in a later foam optimization stage, intermolecular crosslinking is promoted to release micromolecular formaldehyde in advance, and the formaldehyde content in the product is further reduced.
6. The existing traditional melamine foam optimizes process conditions, so that the cost is high, the aging degree of the melamine-based foam plastic is aggravated in a high-temperature environment for a long time, and the produced low-formaldehyde product has the defects of easy powder falling, obvious yellowing phenomenon and the like. The technical scheme of the invention solves various defects existing in the traditional melamine foam optimization process conditions by improving the traditional melamine foam optimization process conditions.
In conclusion, the technical scheme of the invention is that the expandable low-formaldehyde melamine-based resin is prepared by improving the prior art, then the optimized emulsifier, foaming agent, compound curing agent and other performance stabilizer are added into the obtained resin for high-speed emulsification, and the melamine-based foam M1 is obtained by foaming with microwaves with certain power after emulsification; after the M1 foam is subjected to hot steam heat treatment and remote microwave radiation drying optimization, the environment-friendly melamine-based foam plastic of the invention is obtained. The product of the invention is detected by Zhejiang textile testing research institute (national textile and clothing product quality supervision and inspection center) according to ISO14184.1-2011, and no formaldehyde is detected. In addition, the melamine-based foam plastic product prepared by the method has the advantages that various physical performance indexes are obviously improved.
Fourthly, the specific implementation mode:
the invention is further illustrated by the following examples, which do not limit the scope of the invention.
Example 1:
the invention relates to a preparation method of environment-friendly melamine-based foam plastic, which comprises the following detailed steps:
(1) preparation of expandable low-formaldehyde melamine-based resin:
a. melamine, paraformaldehyde and water are used as main raw materials; expressed by weight Kg, the addition amounts of the three main raw materials are 600Kg of melamine, 328.6Kg of paraformaldehyde and 310Kg of desalted water respectively;
b. weighing melamine, paraformaldehyde and water according to the addition amount of the three main raw materials in the step a, adding the three raw materials into a reaction kettle, uniformly stirring, adding 3Kg of modified monomer benzoguanamine, and adding 20% by mass of sodium hydroxide solution to adjust the pH value to 8-9; heating the steam until the temperature of the reaction solution is 90 ℃, adjusting the steam introduction amount to be small, reacting for 3 hours at constant temperature, closing the steam inlet valve, and finishing the reaction;
c. after the reaction in the step b, cooling the obtained reaction liquid by using cold water, stopping cooling the cold water when the temperature is reduced to 40 ℃, then adding 2Kg of formaldehyde-removing functional monomer 2-imidazolidinone, continuously stirring and reacting for 2 hours under the reaction temperature condition, and then cooling the cold water to 0 ℃ to obtain the expandable low-formaldehyde melamine-based resin;
(2) preparation of mixed auxiliary agent:
adding 56Kg of 20 percent sodium dodecyl benzene sulfonate, 62Kg of compound curing agent (20 Kg of formic acid and 42Kg of methylhexahydrophthalic anhydride) and 80Kg of n-pentane into a 300Kg auxiliary agent reaction kettle in sequence, stirring for 30 minutes at 720 r/s, uniformly stirring and mixing various auxiliary agents, and then adjusting the rotating speed to 300 r/s for slow stirring for later use;
(3) preparation of melamine-based foam M1:
cooling the expandable low-formaldehyde melamine resin prepared in the step (1) to 0 ℃ through a single screw, and then feeding the expandable low-formaldehyde melamine resin into a double-screw machine through a metering screw, wherein the flow rate of the metering screw is 2.2 Kg/min; the mixed auxiliary agent obtained in the step (2) and the expandable low-formaldehyde melamine-based resin enter a double-screw machine through a metering pump at the same time, and the flow of the metering pump is 410 g/min; mixing the expandable low-formaldehyde melamine-based resin and the mixing auxiliary agent in a double-screw machine for high-speed emulsification (the rotating speed of a screw is 110 revolutions per minute, and the time is 2 minutes); after the mixture is emulsified by a screw, the temperature of the mixture is reduced to 0 ℃, the mixture enters a material distribution device, the material distribution amount is 1000g/min, the conveying speed of a material distribution belt is 0.5M/min, the mixture enters a microwave oven for foaming, the microwave foaming power is 100Kw, the microwave foaming time is 30 min, and melamine-based foam M1 is obtained after foaming;
(4) optimization of the melamine-based foam M1:
the melamine-based foam M1 obtained in the step (3) firstly enters a superheated steam drying stage, and superheated steam at 160 ℃ enters from the upper part of a drying box body for drying; the drying box body is 10 meters long, 1 meter high and 1.2 meters wide, a grid belt is arranged on the bottom of the box body, the belt speed is 0.1 meter/minute, meshes with the diameter of 0.5cm are fully distributed in the bottom of the box body within 0.5 meter from the central line, and the negative pressure environment is-150 pa in the drying process (the stage enables small molecular formaldehyde and foaming agent generated in the early stage foaming stage to overflow together with superheated steam);
after superheated steam drying, the process enters a microwave drying stage, the microwave power is 3KW, the belt transmission rate is 0.1 m/min, the box body length is 15 m, the box body temperature of a microwave oven is 110 ℃ (the stage aims at removing moisture and sterilizing the melamine-based foamed plastic), and the product of the environment-friendly melamine-based foamed plastic is obtained after microwave drying.
The performance index detection of the related products of the invention: detecting free aldehyde in the expandable low-formaldehyde melamine-based resin according to the standard of GB/T5543-2006 determination of total aldehyde content, free formaldehyde content and hydroxymethyl content of a resin finishing agent, detecting the formaldehyde content of the melamine-based foam plastic according to the standard of ISO14184.1-2011 determination first part of formaldehyde of textiles, and detecting physical performance indexes by Q/PLH001-2017 (standard of foam enterprises); the temperature resistance detection method is characterized in that samples with the same size and shape are placed in a muffle furnace for high-temperature treatment, and the quality, the shape and the performance of the samples are not changed after 72 hours at a certain temperature, namely the samples can exist for a long time at the temperature.
The product of the invention adopts a standard detection process of ISO14184.1-2011 first part of the determination of textile formaldehyde: and when the content of the formaldehyde in the detected sample is less than or equal to 32mg/kg, the detected result is regarded as undetected.
The data of the relevant performance test experiment of the product obtained in this example are detailed in table 1.
TABLE 1 data of the related Performance test of the product obtained in this example
Example 2: the same as example 1 except that:
the preparation method of the environment-friendly melamine-based foam plastic is basically the same as that of the embodiment 1, and the difference is that:
(1) preparation of expandable low-formaldehyde melamine-based resin:
a. the addition amounts of the three main raw materials are respectively 600Kg of melamine, 357.1Kg of paraformaldehyde and 319Kg of desalted water, which are expressed by weight Kg;
b. then, sodium hydroxide solution with the mass percentage concentration of 25% is adopted to adjust the pH value to be 8-9, and then 6Kg of modified monomer superfine polyimide resin powder is added; when the temperature of the steam rises to 95 ℃, regulating the steam inlet amount to perform constant temperature reaction for 2.5 hours, closing the steam inlet valve, and finishing the reaction;
c. then 6.4Kg of aldehyde-removing functional monomer 1, 3-dimethyl-2-imidazolidinone is added;
(2) preparing a mixed auxiliary agent:
adding 60Kg of 40 percent of ethoxylated fatty acid methyl ester sodium sulfonate, 64Kg of compound curing agent (21 Kg of formic acid and 43Kg of phthalic anhydride) and 84Kg of n-pentane into a 300Kg of assistant reaction kettle;
(3) preparation of melamine-based foam M1:
then enters a double-screw machine through a metering screw, and the flow rate of the metering screw is 2.3 Kg/min; the mixed auxiliary agent obtained in the step (2) and the expandable low-formaldehyde melamine-based resin enter a double-screw machine simultaneously through a metering pump, and the flow of the metering pump is 415 g/min; the conveying speed of the cloth belt is 1M/min, the microwave foaming power is 110Kw, the microwave foaming time is 25 min, and melamine-based foam M1 is obtained after foaming;
(4) optimization of the melamine-based foam M1:
the upper surface of the bottom of the box body is provided with a grid belt with the belt speed of 0.2 m/min,
after the superheated steam drying, the microwave drying stage is carried out, wherein the microwave power is 3KW, and the belt conveying speed is 0.2 m/min.
The data of the relevant performance test experiment of the product obtained in this example are detailed in table 2.
TABLE 2 data of the related performance tests of the products obtained in this example
Example 3: the same as example 1 except that:
the preparation method of the environment-friendly melamine-based foam plastic is basically the same as that of the embodiment 1, and the difference is that:
(1) preparation of expandable low-formaldehyde melamine-based resin:
a. expressed by weight Kg, the addition amounts of the three main raw materials are 600Kg of melamine, 400Kg of paraformaldehyde and 340Kg of desalted water respectively;
b. then, sodium hydroxide solution with the mass percentage concentration of 25% is adopted to adjust the pH value to be 8-9, and 9Kg of modified monomer tri- (2-hydroxyethyl) isocyanate is added; when the temperature of the steam rises to 100 ℃, regulating the steam introduction amount to perform constant temperature reaction for 2 hours, closing the steam inlet valve, and finishing the reaction;
c. then 13.4Kg of melamine which is a monomer with the function of removing aldehyde is added,
(2) preparing a mixed auxiliary agent:
adding 64Kg of 25 percent of alkyl sodium naphthalene sulfonate, 66Kg of compound curing agent (wherein, 22Kg of formic acid and 44Kg of phthalic anhydride) and 86Kg of n-pentane into a 300Kg auxiliary agent reaction kettle;
(3) preparation of melamine-based foam M1:
then enters a double-screw machine through a metering screw, and the flow rate of the metering screw is 2.2 Kg/min; the mixed auxiliary agent obtained in the step (2) and the expandable low-formaldehyde melamine-based resin enter a double-screw machine simultaneously through a metering pump, and the flow of the metering pump is 420 g/min; the conveying speed of the cloth belt is 1M/min, the microwave foaming power is 110Kw, the microwave foaming time is 25 min, and melamine-based foam M1 is obtained after foaming;
(4) optimization of the melamine-based foam M1:
the upper surface of the bottom of the box body is provided with a grid belt with the belt speed of 0.3 m/min,
after the superheated steam drying, the microwave drying stage is carried out, wherein the microwave power is 3KW, and the belt conveying speed is 0.3 m/min.
The data of the relevant performance test experiment of the product obtained in this example are detailed in table 3.
TABLE 3 data of the related performance tests of the products obtained in this example
Example 4: the same as example 1 except that:
the preparation method of the environment-friendly melamine-based foam plastic is basically the same as that of the embodiment 1, and the difference is that:
(1) preparation of expandable low-formaldehyde melamine-based resin:
a. the addition amounts of the three main raw materials are 600Kg of melamine, 428Kg of paraformaldehyde and 343Kg of desalted water respectively expressed by weight Kg;
b. then, adjusting the pH value to 8-9 by adopting a sodium hydroxide solution with the mass percentage concentration of 30%, and then adding 5Kg of modified monomer sodium tetraborate; when the temperature of the steam rises to 100 ℃, regulating the steam introduction amount to perform constant temperature reaction for 2 hours, closing the steam inlet valve, and finishing the reaction;
c. then 27.42Kg of aldehyde-removing functional monomer sodium thiosulfate is added,
(2) preparing a mixed auxiliary agent:
adding 64Kg of secondary alkyl sodium sulfonate with the concentration of 16 percent, 72Kg of compound curing agent (wherein, 24Kg of formic acid and 48Kg of maleic anhydride) and 90Kg of n-pentane into a 300Kg of auxiliary agent reaction kettle;
(3) preparation of melamine-based foam M1:
then enters a double-screw machine through a metering screw, and the flow rate of the metering screw is 2.4 Kg/min; the mixed auxiliary agent obtained in the step (2) and the expandable low-formaldehyde melamine-based resin enter a double-screw machine through a metering pump at the same time, and the flow of the metering pump is 430 g/min; the conveying speed of the cloth belt is 1M/min, the microwave foaming power is 110Kw, the microwave foaming time is 25 min, and melamine-based foam M1 is obtained after foaming;
(4) optimization of the melamine-based foam M1:
the upper surface of the bottom of the box body is provided with a grid belt with the belt speed of 0.5 m/min,
after superheated steam drying, the microwave drying stage is carried out, wherein the microwave power is 3KW, and the belt conveying speed is 0.5 m/min.
The data of the relevant performance test experiments of the product obtained in this example are detailed in table 4.
TABLE 4 data of the related performance tests of the products obtained in this example
Claims (8)
1. The preparation method of the environment-friendly melamine-based foam plastic is characterized by comprising the following steps:
(1) preparation of expandable low-formaldehyde melamine-based resin:
a. melamine, paraformaldehyde and water are used as main raw materials; the addition amounts of the three main raw materials are 40-60 parts of melamine, 25-35 parts of paraformaldehyde and 25-40 parts of water respectively in parts by weight;
b. weighing melamine, paraformaldehyde and water according to the proportion of the three main raw materials in the step a, adding the weighed three raw materials into a reactor, adding a modified monomer, adding a sodium hydroxide solution to adjust the pH value to 8-9, heating by adopting steam, and reacting at constant temperature for 1-3 hours when the reaction temperature is increased to 80-100 ℃;
the addition amount of the modified monomer is 0.5-5% of the addition mass of the raw material melamine;
the modified monomer is benzoguanamine, superfine polyimide resin powder or tris- (2-hydroxyethyl) isocyanurate;
c. after the reaction in the step b, cooling the temperature of the obtained reaction liquid to 20-40 ℃, then adding an aldehyde-removing functional monomer, continuously stirring and reacting for 1-3 hours under the reaction temperature condition, and obtaining the expandable low-formaldehyde melamine-based resin after the reaction;
the addition amount of the formaldehyde-removing functional monomer is 0.1-5% of the addition mass of melamine;
(2) preparation of mixed auxiliary agent:
adding 25-35 parts of emulsifier, 30-40 parts of compound curing agent and 40-55 parts of foaming agent into an auxiliary agent reaction kettle in sequence, and quickly stirring and uniformly mixing; after uniformly mixing, slowly stirring for later use;
(3) preparation of melamine-based foam M1:
cooling the expandable low-formaldehyde melamine resin prepared in the step (1) to 0 ℃ through a single screw, and then feeding the expandable low-formaldehyde melamine resin into a double-screw machine through a metering screw, wherein the flow rate of the metering screw is 1.5-2.5 Kg/min; the mixed assistant obtained in the step (2) and the expandable low-formaldehyde melamine-based resin enter a double-screw machine simultaneously through a metering pump, and the flow of the metering pump is 400-; mixing the expandable low-formaldehyde melamine-based resin and the mixing auxiliary agent in a double screw extruder for high-speed emulsification, uniformly distributing the emulsified material, then sending the material into a microwave oven for foaming, wherein the microwave foaming power is 90-120Kw, the microwave foaming time is 15-30 minutes, and the melamine-based foam M1 is obtained after microwave irradiation foaming;
(4) optimization of melamine based foams:
drying the melamine-based foam M1 obtained in the step (3) by using superheated steam; after the superheated steam is dried, the product is dried again by a microwave oven, and finally the environment-friendly melamine-based foam plastic product is obtained.
2. The method for preparing environment-friendly melamine-based foam plastic according to claim 1, wherein: the mass percentage concentration of the sodium hydroxide solution is 10-30%.
3. The method for preparing environment-friendly melamine-based foam plastic according to claim 1, wherein: the aldehyde-removing functional monomer is at least one of 2-imidazolidinone, N-chloroformyl-2-imidazolidinone, 1, 3-dimethyl-2-imidazolidinone, N-acetyl-2-imidazolidinone, melamine, hydrogen peroxide, sodium thiosulfate, nano titanium dioxide, acetanilide, hexamethylene diamine, thiourea, N-methylethylamine, ammonia water and hydrazine carbonate.
4. The method for preparing environment-friendly melamine-based foam plastic according to claim 1, wherein: the emulsifier in the step (2) is an anionic surfactant;
the compound curing agent is a mixture of an organic acid and a potential high-temperature curing agent, and the mass ratio of the organic acid to the potential high-temperature curing agent is 1: 1-3;
the latent high-temperature curing agent is methyl hexahydrophthalic anhydride, phthalic anhydride, dicyandiamide, ethylene urea, polyimide, maleic anhydride or polyacrylic acid.
5. The method for preparing environment-friendly melamine-based foam plastic according to claim 4, wherein:
the anionic surfactant is any one of sodium fatty alcohol sulfate, sodium ethoxylated fatty acid methyl ester sulfonate, sodium alkyl naphthalene sulfonate, secondary alkyl sodium sulfonate, alpha-sodium alkenyl sulfonate, sodium dodecyl benzene sulfonate, sodium fatty alcohol polyglycol ether sulfate, sodium lauryl polyoxyethylene ether sulfate, alpha-sulfo fatty acid methyl ester, sodium cocoyl hydroxyethyl sulfonate and sodium dodecyl alcohol polyoxyethylene ether carboxylate;
the organic acid is acetic acid, oxalic acid, formic acid, p-toluenesulfonic acid or 2-acrylamido-2-methylpropanesulfonic acid;
the foaming agent is n-pentane.
6. The method for preparing environment-friendly melamine-based foam plastic according to claim 1, wherein:
the temperature of the microwave oven body in the step (3) is 70-100 ℃.
7. The method for preparing environment-friendly melamine-based foam plastic according to claim 1, wherein: in the superheated steam drying process in the step (4), the length of a box body in a drying section is 10 meters, the height of the box body is 1 meter, the width of the box body is 1.2 meters, a grid belt is arranged on the upper surface of the bottom of the box body, the belt speed is 0.1-0.5 meter/minute, and meshes with the diameter of 0.5cm are fully distributed in the position, which is 0.5 meter away from a central line, of the bottom of the box body; the negative pressure environment in the drying process is-150 pa, and the temperature of the superheated steam is 160 ℃.
8. The method for preparing environment-friendly melamine-based foam plastic according to claim 1, wherein:
in the secondary drying process of the microwave oven, the microwave power is 1-5KW, the conveying speed of the belt is 0.1-0.5 m/min, and the temperature of the box body of the microwave oven is 80-120 ℃.
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| CN115058095B (en) * | 2022-07-01 | 2024-04-23 | 濮阳绿宇新材料科技股份有限公司 | Preparation method of light wave-absorbing sound-absorbing foam |
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| CN1903934A (en) * | 2005-07-27 | 2007-01-31 | 北京绿寰宇化工有限公司 | Production method of nanometer material modified toughened melamine foamed plastic |
| CN104250386A (en) * | 2014-09-25 | 2014-12-31 | 四川金象赛瑞化工股份有限公司 | Preparation method of flame-retardant melamine hard foam |
| CN105693965A (en) * | 2016-03-18 | 2016-06-22 | 江南大学 | Hard closed melamine foam and preparing method thereof |
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| CN1903934A (en) * | 2005-07-27 | 2007-01-31 | 北京绿寰宇化工有限公司 | Production method of nanometer material modified toughened melamine foamed plastic |
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